How to Fertilize pineapple orchid?
Half-strength orchid feed every few weeks in growth

pineapple orchid · Dendrobium densiflorum
Plants are best grown in a pot in an epiphytic, medium grade, bark-based potting mix with added perlite, moss, or coir. As with many orchids, they grow best when the roots are slightly restricted. Therefore, avoid over-potting or frequent root disturbance. It is a cool to warm-growing orchid with average temperatures between 16-25°C. It can be grown similarly to Moth Orchid (Phalaenopsis) but requires much brighter conditions. Provide indirect light and higher humidity by misting regularly in spring and summer, then move the plant to a bright, room in autumn and winter. Reduce watering and feeding until warmer temperatures initiate new growth in spring. See indoor orchid cultivation
Half-strength orchid feed every few weeks in growth